May 30, 2013 in Nation/World

Feathered fossil found by scientists

Amina Khan Los Angeles Times
 
Associated Press photo

An image shows the skeleton of a recently discovered dinosaur dubbed Aurornis xui that roamed China during the middle to late Jurassic period.
(Full-size photo)

LOS ANGELES – When did birds first emerge from among the dinosaurs? It’s an argument that has plagued paleontologists and cast a shadow over the reputation of Archaeopteryx, a feathered dinosaur that has long been considered the earliest known bird.

Now, scientists say they found an even older feathered dinosaur - one that re-establishes Archaeopteryx as part of the bird lineage even as it may simultaneously dethrone Archaeopteryx as the earliest known “bird.” The study, published online in the journal Nature, provides a key link in the evolutionary chain of events that led from dinosaurs to birds.

“It pushes (back) the origins of birds - or origin of animals that are very closely related to the bird,” said Luis Chiappe, a vertebrate paleontologist at the Natural History Museum of Los Angeles who was not involved in the paper. “And that’s quite exciting.”

But some say the fossil may just represent a birdlike dinosaur, not a true bird – and in any case, could have been altered before scientists had a chance to study it.

The new find, christened Aurornis xui, was discovered in northeastern China in the Liaoning Province. The 20-inch, chicken-sized fossil is estimated to be about 160 million years old, about 10 million years older than Archaeopteryx.

After a thorough examination of the fossil, researchers from Europe and China constructed a computer-generated family tree that puts both Aurornis and Archaeopteryx in the Avialae family – the group of dinosaurs whose only living representatives are birds.

“Around the origin of birds 160 million or so years ago, there were many fossils that were experimenting with birdness – getting more and more birdlike,” Chiappe said.

The study authors argue that Aurornis represents the earliest known bird, but other scientists say it could be part of a group of birdlike dinosaurs that were developing feathers and birdlike features but never quite got off the ground, evolutionarily speaking.


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